The present invention relates to an extruder for extruding a rubber compound to make profiled products.
Various categories of machines are known for extruding rubber. One such category comprises extruders commonly called "roller-die extruders" which make it possible to extrude, in long lengths, a product with a constant profile. This profile, i.e. the cross section of the extruded rubber product, is defined in this type of machine, on the one hand, by a roller onto which the rubber is extruded and, on the other hand, by a wall which acts cooperatively with this roller in order to define an extrusion orifice.
In the field of the manufacture of tires, profiled semifinished products consisting of rubber compounds are produced. It is sought to make the continuous production of tires more precise. This manufacturing precision depends in particular on meeting the dimensions of rubber products, the assembly of which constitutes the tire. The "conventional" roller-die extruder, that is to say one such as that described above, does not, by itself, provide such precision.
U.S. Pat. No. 3,871,810 describes a roller-die extruder which includes, upstream of the extrusion orifice, a chamber for channelling the rubber stream. This chamber consists of tooling which includes a series of successive profiles in order for the profile of the rubber compound to be precisely matched to the profile defined by the extrusion orifice. The profile of the extruded product obtained is then very precise. However, this arrangement, using complex equipment which has to be perfectly dimensioned, is, on the one hand, very expensive and, on the other hand, requires very precise adjustment. What is more, changing to the extrusion of another product of a different size becomes a lengthy and expensive operation since it is then no longer a question of just changing the stationary wall element but also the complex tooling constituting the channelling chamber.